Electronic devices such as laptop PCs, tablet PCs, digital cameras, and mobile phones, which are portable while being used by the user are rapidly increasing in recent years. Many of these electronic devices have therein a rechargeable battery, which requires periodical charging. To facilitate the work for charging the rechargeable battery of an electronic device, there are an increasing number of devices for charging rechargeable batteries by using a power-supplying technology (wireless power transmission technology) that performs wireless power transmission between a power-supplying device and a power-receiving device mounted in an electronic device.
Examples of such a wireless power transmission technology includes a technology that performs power transmission by means of resonance phenomena between resonators provided to the power-supplying device and the power-receiving device (e.g. see PTL 1).
According to the above-described wireless power transmission technology, a magnetic field is generated in the vicinity of the resonators of the power-supplying device and the power-receiving device, when the resonator are resonated with each other. Consequently, an eddy current occurs due to the magnetic field in a power-supplying device, a rectifier provided inside or outside the power-receiving device, a rechargeable battery, or another electronic device and heat is generated therefrom, with the result that an adverse effect may occur in the rectifier, the rechargeable battery, or the electronic device.
To solve the above-described problem caused by the magnetic field, for example, PTL 2 recites a power transmission system which is able to reduce the leaked magnetic field in a power-supplying device when power transmission is conducted through contactless power supply. Furthermore, PTL 3 recites a power transceiving device which is able to reduce the magnetic field between a power-supplying coil and a power-receiving coil.